From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 122FCC433FE for ; Mon, 18 Apr 2022 12:32:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239144AbiDRMeg (ORCPT ); Mon, 18 Apr 2022 08:34:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52964 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239828AbiDRMda (ORCPT ); Mon, 18 Apr 2022 08:33:30 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1171E1C10C; Mon, 18 Apr 2022 05:26:52 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 97A3660FF1; Mon, 18 Apr 2022 12:26:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 70DA5C385AC; Mon, 18 Apr 2022 12:26:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650284811; bh=hnXxtEBUA5ZxcilPT0tseZET3rfXT3b/XiaIGhqWjCs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tdhGIgA2WouvEFCI9ck1Lmy8q+5+kqv3z+FfcFP6fxZf6qEoYzylb7SFuP5Fnqbkm q4uHzwUuQk/GCOBA8wNKTH3lK/BP4hHJP553e/KfOEjDH1pFBiGu2gQNEidIMGKZai AwNVHViaxeSzLywrH5u8l3FoLzPuPNKj7zFDFHco= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Takashi Iwai Subject: [PATCH 5.15 016/189] ALSA: core: Add snd_card_free_on_error() helper Date: Mon, 18 Apr 2022 14:10:36 +0200 Message-Id: <20220418121200.973418134@linuxfoundation.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220418121200.312988959@linuxfoundation.org> References: <20220418121200.312988959@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Takashi Iwai commit fee2b871d8d6389c9b4bdf9346a99ccc1c98c9b8 upstream. This is a small helper function to handle the error path more easily when an error happens during the probe for the device with the device-managed card. Since devres releases in the reverser order of the creations, usually snd_card_free() gets called at the last in the probe error path unless it already reached snd_card_register() calls. Due to this nature, when a driver expects the resource releases in card->private_free, this might be called too lately. As a workaround, one should call the probe like: static int __some_probe(...) { // do real probe.... } static int some_probe(...) { return snd_card_free_on_error(dev, __some_probe(dev, ...)); } so that the snd_card_free() is called explicitly at the beginning of the error path from the probe. This function will be used in the upcoming fixes to address the regressions by devres usages. Fixes: e8ad415b7a55 ("ALSA: core: Add managed card creation") Cc: Link: https://lore.kernel.org/r/20220412093141.8008-2-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- include/sound/core.h | 1 + sound/core/init.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 29 insertions(+) --- a/include/sound/core.h +++ b/include/sound/core.h @@ -284,6 +284,7 @@ int snd_card_disconnect(struct snd_card void snd_card_disconnect_sync(struct snd_card *card); int snd_card_free(struct snd_card *card); int snd_card_free_when_closed(struct snd_card *card); +int snd_card_free_on_error(struct device *dev, int ret); void snd_card_set_id(struct snd_card *card, const char *id); int snd_card_register(struct snd_card *card); int snd_card_info_init(void); --- a/sound/core/init.c +++ b/sound/core/init.c @@ -209,6 +209,12 @@ static void __snd_card_release(struct de * snd_card_register(), the very first devres action to call snd_card_free() * is added automatically. In that way, the resource disconnection is assured * at first, then released in the expected order. + * + * If an error happens at the probe before snd_card_register() is called and + * there have been other devres resources, you'd need to free the card manually + * via snd_card_free() call in the error; otherwise it may lead to UAF due to + * devres call orders. You can use snd_card_free_on_error() helper for + * handling it more easily. */ int snd_devm_card_new(struct device *parent, int idx, const char *xid, struct module *module, size_t extra_size, @@ -235,6 +241,28 @@ int snd_devm_card_new(struct device *par } EXPORT_SYMBOL_GPL(snd_devm_card_new); +/** + * snd_card_free_on_error - a small helper for handling devm probe errors + * @dev: the managed device object + * @ret: the return code from the probe callback + * + * This function handles the explicit snd_card_free() call at the error from + * the probe callback. It's just a small helper for simplifying the error + * handling with the managed devices. + */ +int snd_card_free_on_error(struct device *dev, int ret) +{ + struct snd_card *card; + + if (!ret) + return 0; + card = devres_find(dev, __snd_card_release, NULL, NULL); + if (card) + snd_card_free(card); + return ret; +} +EXPORT_SYMBOL_GPL(snd_card_free_on_error); + static int snd_card_init(struct snd_card *card, struct device *parent, int idx, const char *xid, struct module *module, size_t extra_size)